I'm surprised only 84% of the traffic is Windows users.
You are also implying that developers using windows are all second rate.
If you subtract that quotient from the general pool of "Windows developers" it becomes much more of a fair comparison.
Yes, there's useful things on w3schools, but like picking through a trash heap full of rusted bicycles and used syringes, it's a dangerous expedition. You might pick up some awful bad habits along the way.
When even the basics are wrong you're not getting refreshed much. Especially when adding three letters ('mdn') to the query at the end gives you a much better resource by all metrics.
Actually, the implication is that second rate developers are Windows users. Which is a very different statement.
That's not referring to Windows users in particular.